What distinguishes a non-rebreather mask from a partial rebreather mask?

• A. Non-rebreather uses a nasal prong
• B. Non-rebreather has a reservoir bag but no valve
• C. Partial has a valve
• D. Non-rebreather has a reservoir bag with a one-way valve

Answer: (D)

The difference lies in how the breathing circuit directs air and prevents rebreathing. A non-rebreather mask includes a reservoir bag and, crucially, a one-way valve that stops exhaled air from entering the bag. During inhale, you draw gas from the reservoir; exhaled air exits through side ports, so you’re mainly inhaling fresh oxygen from the bag. This setup can deliver very high oxygen concentrations when flow is adequate.

A nasal prong setup isn’t used with a non-rebreather; that’s a different delivery method entirely. A statement that the mask has a bag with no valve would describe a partial rebreather, which allows some exhaled air to mix back in. Conversely, saying the partial rebreather has a valve is incorrect because it typically lacks the one-way valve that characterizes the non-rebreather.